ALMOST twice as much water as Cubbie Station's 460 billion litre entitlement is effectively sent overseas each year in the form of irrigated cotton.

As governments continue to bicker over a plan to save the Murray, research released today shows an average 940 gigalitres of water is diverted from the Murray-Darling Basin to grow cotton for export.

Friends of the Earth campaigns co-ordinator Cam Walker, who commissioned the research, said debate about Cubbie Station should not be about the nationality of its owners, but rather the amount of water it was sending overseas in the form of cotton exports.

"Instead of endless debates about who owns our cotton farms, we should be asking if it is appropriate for them to send so much of our precious water overseas in the first place," Mr Walker said. "Science clearly tells us that current extraction rates are unsustainable and will lead to widespread ecological collapse across the Murray-Darling Basin.

"Cotton is a highly water intensive crop and the largest user of irrigation water in the basin."

The Federal Government last month approved the sale of Cubbie Station to a Chinese consortium.

The Friends of the Earth research is based on Federal Government data on annual cotton exports and water from 2005 to 2011, and calculates the volume of water used in Australia's export cotton crop.

Cotton is only grown in NSW and Queensland.

In 2010-11, almost 1800 gigalitres of water was diverted for growing cotton in the basin, representing almost 40 per cent of all irrigation water used.

"It is crucial that water trade policy in the Murray-Darling basin be examined and water saving initiatives in this area be more thoroughly analysed and effectively implemented," the report says. News Ltd revealed on Monday that almost 1000 new cotton and rice farms with a combined land area almost 1½ times the size of Adelaide had sprung up interstate in a year.

SA Senator Nick Xenophon said the report was another example of inefficient water use that would effect both the environment and communities in the long term. "The more cotton and rice farms that sprout up, the more difficult it will be for South Australia to get a fair deal in the long run," he said.